Field of the Invention
The present invention relates to a water-based ink set for ink-jet recording and an ink-jet recording apparatus.
Description of the Related Art
Ink-jet recording is conventionally performed by jetting a water-based black ink and water-based color inks from an ink-jet head to record a black recording portion and color recording portions. Such ink-jet recording may cause bleeding at a boundary between the black recording portion and each color recording portion, and the blurred black ink deteriorates recording quality. The ink-jet recording may use a water-based pigment ink containing a pigment as colorant. Since the pigment is insoluble in water, jetting stability is strongly required for the ink-jet recording using a water-based ink set including the water-based pigment ink. To prevent the bleeding and enhance the jetting stability, there is proposed a water-based ink set for ink-jet recording in which the content of a water-soluble solvent in each of the water-based black pigment ink and the water-based color inks is regulated. Regarding ink-jet recording apparatuses, they typically include a maintenance unit with a wipe member and the like which wipes the water-based ink adhering to an ink jetting surface of an ink-jet head.
If water-based pigment inks of multiple colors constituting a water-based ink set for ink-jet recording are brought into contact with each other, for example, on the ink jetting surface of the ink-jet head, their pigments may aggregate or coagulate to generate their aggregations or coagulation. If the aggregations, which are generated by mixing the water-based pigment inks with each other, are present in great quantity, for example, wiping or collecting of the aggregations becomes difficult when the maintenance using the maintenance unit is performed. This problem deteriorates maintenability. Thus, it is desired to develop a novel water-based ink set for ink-jet recording which is less likely to cause the bleeding at a boundary between a black recording portion and each color recording portion and to generate a pigment aggregation when the water-based pigment inks are mixed with each other in the ink-jet recording apparatus.
In view of the above, an object of the present teaching is to provide a water-based ink set for ink-jet recording which is less likely to cause the bleeding at a boundary between a black recording portion and each color recording portion and to generate an aggregation or coagulation during maintenance.